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: Octagon Shape 20x15 mm Gems
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Gemtype Color Shape Weight Size Date Clarity Price Origin
You Selected (3): Octagon Shape 20x15 mm Gems Clear All
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ID: 4731381 pcs
thumb image of 23.3ct Octagon Step Cut Brown Smoky Quartz (ID: 473138)
23.26 ct Smoky Quartz
19.9 x 15 mm
$ 16.98
Item in Stock
ID: 4919022 pcs
thumb image of 41.3ct Octagon Cabochon Black Gray Hematite (ID: 491902)
41.25 ct Hematite
19.8 x 15.1 mm
$ 36.71
Item in Stock
ID: 4700821 pcs
thumb image of 34.1ct Octagon Step Cut Lemon Quartz (ID: 470082)
34.11 ct Quartz
19.9 x 14.7 mm
$ 35.82
Item in Stock
Octagon Shape 20x15 mm Gems
Some people by gems by color or price, but for many, it is best to buy gems by shape and size - especially if you're in need of a gem to replace a previous item that was lost or damaged. Calibrated Octagon shape / Emerald-Cut, faceted and cabochon gems available now in 20 x 15 mm size range. Shop a wide range of calibrated gemstones by size online at wholesale from GemSelect.

As a general guideline, when it comes to 'calibrated' gems, they are not usually expected to be cut to exact measurements. For calibrated gemstones weighing under one carat, most jewelry settings will accommodate a gem which is within 0.2 mm of the calibrated size in order to fit a standard setting. For gemstones that weigh over one carat, a larger variance is acceptable, often round shape settings will allow 0.3 mm or slightly higher even. This small variance can usually be accommodated for most standard style settings. Round-cut gemstones should also have a greater variance in acceptable size when it comes to calibration; in fact it is usually possible to mount a round stone of any size in the closest standard setting.

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Size and Weight

Gems are always measured in Millimeter (mm)

Dimensions are given as;
length x width x depth,
except for round stones which are;
diameter x depth

Select gems by size, not by weight!
Gem varieties vary in density, so carat weight is not a good indication of size

Note: 1ct = 0.2g

Size Comparison Chart